Method and apparatus for adapting a number of bearers to a service

ABSTRACT

The invention relates to the implementation of changing a service between a user equipment (UE) and a Telecommunications network operating according to Universal Mobile Telecommunication System standards by using a known radio bearer assignment message for indicating the change of use of a connection from a first service to a second service.

FIELD OF INVENTION

The invention relates to a method for the adaptation of a number ofbearers in the case that a service on a connection is changed. Itfurther relates to a radio network controller, a mobile servicesswitching centre, and a user equipment adapted to perform the adaptationand a radio access bearer assignment message used for performing themethod.

DESCRIPTION OF PRIOR ART

The changing of a service can be used for example for the implementationof call hold and call waiting services. Call hold and call waitingservices are used to enable a subscriber who already is active in a callto accept a further call. Therefore the further call is offered to thesubscriber as a waiting call. The subscriber decides either to rejectthe further call or to put the active call on hold and to accept thefurther call. The handling of this feature is described in more detailin the 3GPP technical specifications 22.083, version 3.0.1 publishedOctober 1999, 23.083 version 3.1.0 published January 2000, and 24.083version 3.0.0 published May 1999.

In the abovementioned documents it is a prerequisite that the bearerused for the active call can also be used for the further call.

The changing of radio bearer between user equipment is disclosed in the3GPP specification TS 25.331 Version 3.1.0 published January 2001.However, said specification does not disclose that the change of radiobearer might be used for service alteration.

The initiation or indication of a changing of radio bearer is describedin the 3GPP specification TS 25.413, Version 3.0.0. However, also thisspecification fails to describe the use of said changing for servicealteration.

The evolution of third generation networks like UMTS (Universal MobileTelecommunication System) or cellular communication systems like GPRS(General Packet Radio System), however, permits the set-up of dataconnections as well as speech connections to user equipment.

This may lead to a situation wherein a subscriber with an active dataconnection is offered a speech connection and vice versa, a so-calledinhomogeneous call waiting situation.

It is not disclosed in the prior art, how to implement call waiting andcall hold supplementary services for these situations. To master aninhomogeneous call waiting call hold situation, a service alteration isnecessary. For the time being, no service alteration forTelecommunications networks operating according to Universal MobileTelecommunication System standards is disclosed.

SUMMARY OF THE INVENTION

It is therefore object of the invention to provide a method for theimplementation of service alteration for a UMTS network.

This problem is solved by the methods of claims 1, 6, 9, and 14, theuser equipment of claim 16, the radio network controller of claim 17,the mobile services switching centre of claim 19 the computer programsof claims 20, 21 and 22, and the use of the methods according to claim23.

Advantageous is the use of a radio bearer assignment message for theindication of the beginning of the adaptation of the number of radiobearers. The radio bearer assignment message is already defined and canbe used with only minor modifications of its definition.

Further advantageous embodiments can be derived from the dependentclaims 2 to 5, 7, 8, 10 to 13, 15, and 18.

Advantageous is that the user equipment keeps the call control contextand the mobility management context according to claim 3 or 8. Thisreduces the effort of adapting the number of radio access bearers.

Further advantageous is the setting up of a connection for the secondservice before the connection for the first service is releasedaccording to claim 5 or 12. By this, always at least one activeconnection between radio network controller and user equipment exists.This has the advantage that context related data are kept automatically.

Advantageous is the dependence of the sequence of call set up andrelease according to claim 13. By this, an operator can decide whichsequence he prefers.

The invented method for adapting a number of radio bearers of aconnection between a user equipment and a Telecommunications networkoperating according to Universal Mobile Telecommunication Systemstandards from a first number of radio bearers appropriate for a firstservice to a second number of bearers appropriate for a second servicecomprises the followings steps. The beginning of the adaptation isindicated by a radio access bearer assignment message that is sent froma mobile services switching centre to a radio network controller. Theradio network controller sends a radio bearer set up message to the userequipment for changing the number of bearers for the connection. Theuser equipment modifies the number of radio access bearers it supportsfor the connection from the first number to the second number. Itacknowledges the modification by sending a radio bearer set up completemessage to the radio network controller. The radio network controllerindicates the completion of the adaptation to the mobile servicesswitching centre by sending a radio bearer assignment complete message.

The method can further comprise the additional steps that the radionetwork controller sends a radio bearer release message for reducing thenumber of bearers to the user equipment. The user equipment reduces thenumber of bearers and acknowledges the reduction to the radio networkcontroller by sending a radio bearer release message.

In a preferred embodiment of the invention the user equipment keeps thecall control context and the mobility management context while changingthe number of bearers.

For any of the described methods also the following additional steps canbe performed. The radio network controller sends a release requestmessage to the mobile services switching centre to release theconnection for the first service. The mobile services switching centrereleases the first connection and sends a release confirm message to theradio network controller. The radio network controller sends anestablishment request message to the mobile services switching centre toestablish a connection for the second service. The mobile servicesswitching centre sets up the connection for the second service and sendsan establishment confirm to the radio network controller to confirm theset up of the connection for the second service.

The invention also relates to a user equipment, a radio networkcontroller and a mobile services switching centre that comprise meansfor performing any of the described methods. It further relates tocomputer programs for controlling a user equipment, a mobile servicesswitching centre and a radio network controller in a way that theyperform any of the described methods.

The invention also provides a synchronisation method for inhomogeneouscall waiting call hold situations. Therefore, the communication betweenuser equipment and radio network controller is performed according toDTAP (Direct Transfer Application Part) signalling as in the cited priorart. In the case of inhomogeneous call waiting/call hold the removal orlinking in of at least one CODEC (COder/DECoder) is a synchronisingevent.

The invention further provides a method for the set up of theconnections. Therefore the RAB (Radio Access Bearer) and at least one RB(Radio Bearer) from the active call is used for the further call.

The detection within an RNC (Radio Network Controller) of a waiting callthat is going to become the active call is performed by using the RABidentification of the former active call and transmitting at least onemodified parameter in association with the RAB identification.

BRIEF DESCRIPTION OF THE DRAWINGS

The following figures show:

FIG. 1: depicts a signal flow for an active voice call and a waitingdata call according to the invention,

FIG. 2: depicts a signal flow for an active data call and a waitingvoice call according to the invention, and

FIG. 3: depicts a signal flow for an active voice call and a waitingdata call according to the invention, wherein AAL2 (ATM Adaptation Layertype 2) signalling between an access node and a core network noderegarding user plane handling has been added to improve theunderstanding by a person skilled in the art.

DETAILED DESCRIPTION OF EMBODIMENTS

In the following the invention is described in more detail by means ofembodiments and figures. Due to the similarity of data and fax callswith respect to the invention, the invention will only be described fordata calls, as the handling of a fax call is equal. Equal referencesigns indicate equal elements.

FIG. 1 depicts a signal flow for a service alteration from an activevoice call to a waiting data call according to the invention. The figureshows a mobile services switching centre MSC, a radio network controllerRNC, and a user equipment UE. The user equipment UE and the mobileservices switching centre MSC already agreed to accept the waiting datacall. The data call will be through connected to the user equipment UEin a transparent mode.

The same signal flow applies for the reactivation of a data call thathas been put on hold after a speech call has been offered as a waitingcall.

A first signal 101 is sent from the core network node MSC to the accessnode RNC comprising a RAB assignment modification, that identifies aradio access bearer that is to be modified by using a RAB identificationRAB id. The RAB identification identifies the RAB that is already usedfor the currently active speech call. The message 101 also comprises RABparameter as defined in the 3GPP technical specification TS25.413,published December 2000. Furthermore the message comprises a user planemode information parameter. In the specification the user plane modeinformation parameter is sent only in the case of a setup. In theinvented method is sent in the case of a modification of a RAB, too.

The receiving radio network controller RNC recognises the radio accessbearer change as it already stored a set of parameters associated to theRAB identification RAB id, and the parameter values received and theparameter values stored differ in at least one parameter value.

In the example the speech connection uses three radio bearers and thedata connection only one radio bearer. The radio network controller RNCsends a radio bearer release message 102 to the user equipment UE torelease two of the three radio bearer, the message comprising a RABinformation to release two radio bearer identified by their radio beareridentification RB id.

The user equipment acknowledges the release of the two radio bearerswith a radio bearer release complete message 103. The user equipmentkeeps the call control and the mobility management contexts establishedfor the formerly active speech call, even in an embodiment of theinvention wherein all radio bearers are released and a new radio beareris set up. The call control context and the mobility management contexthave been created by NAS (Non Access Stratum) signalling, for exampleDTAP signalling.

The radio network controller RNC sends a radio bearer setup message 104to the user equipment UE. In the depicted embodiment of the inventionthe radio bearer set up message is used for the modification of anexisting radio bearer. In a further embodiment of the invention, thebearer is not modified but all bearers are released and a new one is setup. The radio bearer set up message comprises signalling radio bearerinformation setup to list that indicates a radio bearer to setup, a RABinformation to setup list indication a RAB information for setup, and aradio bearer identification. The RAB information to setup was receivedby the access node RNC in the message 101.

The user equipment UE modifies the radio bearer in order to support thedata connection. It acknowledges the modification by sending a radiobearer setup complete message 105 to the radio network controller RNC.

The radio network controller RNC informs the mobile services switchingcentre MSC about the successful adaptation of the connection between theuser equipment UE and the radio network controller RNC by sending a RABassignment response message 106. The assignment response message 106comprises the RAB identification RAB id of the modified RAB.

In an embodiment of the invention, the set up of a new connection isperformed before the release of an existing connection. In saidembodiment, the messages 104 and 105 are sent before the messages 102and 103. In a preferred embodiment, the sequence of release and set updepends on the decision of a decision logic, implemented in the radionetwork controller RNC. The decision of the decision logic can depend onfor example by operator settings, a identification of a user equipmentor a parameter value of a message sent by the mobile services switchingcentre MSC.

FIG. 2 depicts a signal flow for the alteration of an active data calland a waiting voice call according to the invention. The figurecomprises a mobile services switching centre MSC, a radio networkcontroller RNC and a user equipment UE. In the example an active datacall, transmitted for example in the transparent mode, is replaced by aspeech call. The user equipment UE and the core network node UE alreadyagreed to accept the waiting speech call. The speech call will bethrough connected to the user equipment UE replacing the data call asthe active connection. The data call is put on hold.

The same signal flow applies in the case that a data call has been puton hold after a speech call has been offered as a waiting call.

The mobile services switching centre MSC sends a RAB assignment message201 to the radio network controller RNC. The RAB assignment messagecomprises the same parameter as message 101, although at least one ofthem with a different value. The user plane mode information indicatesthat a data call transmitted in transparent mode will be replaced by aspeech call. As the speech call is not transparent at least in the casethat a CODEC linked in.

The radio network controller RNC detects that a waiting call is going toreplace another call as active call from the fact that the RAB parametervalue for a RAB differ from stored parameter values in at least oneparameter value. A RAB identifier identifies the RAB.

As the speech call requires three radio bearers instead of one bearer asthe data call, the radio network controller RNC sends a radio bearersetup message 202 to the user equipment UE. The Radio bearer setupmessage is in this example is used for the modification of the currentlyused radio bearer and the setup of two further radio bearers. Itcomprises a signalling RB (radio bearer) information to setup bearer towhich are identified by three radio bearer identifications. The messagefurther comprises a RAB setup information list with RAB information forsetup. This information has been received by the radio networkcontroller RNC from the mobile services switching centre MSC in message201.

The user equipment UE modifies the existing radio bearer according tothe received information and sets up two further radio bearers. Itacknowledges the execution by sending a radio bearer setup completemessage 203 to the radio network controller RNC.

The radio network controller RNC informs the mobile services switchingcentre MSC about the successful modification and setup of radio bearerby sending a RAB assignment response message 204. The message comprisesthe RAB identification of the RAB that has been modified.

FIG. 3 depicts the signal flow of FIG. 1, with the addition of AAL2signalling between the radio network controller RNC and the mobileservices switching centre MSC.

In a further embodiment of the invention, the mobile services switchingcentre MSC is a media gateway in a core network that supports bearerindependent call control.

The signals 301 Release request, sent from the radio network controllerRNC to the mobile services switching centre MSC and 302 Release confirm,sent in the opposite direction, are used to define the signallingpartners. This is performed by exchanging a destination associationidentification.

In signal 303, Establishment request, sent from the radio networkcontroller RNC to the mobile services switching centre MSC, thetransport address and the transport association on the Iu interface aretransmitted.

The transport address is sent as destination NSAP (Network ServiceAccess Point) service endpoint address and the transport association issent as the server used generated reference.

The message also comprises an origination signalling associationidentification. The connection is identified by the destinationassociation identification.

In an embodiment of the invention, the setup of an AAL.2 (Asynchronoustransfer mode Adaptation Layer Type 2) connection is requested bymessage 303.

The mobile services switching centre MSC acknowledges by returning thedestination and origination association identification in anestablishment confirm message 304.

In an embodiment of the invention, the setup of the AAL.2 connection forthe data call is confirmed by message 304.

In an embodiment of the invention the sequence of the release of aconnection and the establishment of a connection depends on a decisionof a decision logic in the radio network controller RNC. According tothe decision of said logic a new connection may be set up before anotherconnection is released. In that case the messages 104 and 105 are sentbefore the messages 102 and 103; and the messages 304 and 303 are sentbefore the messages 301 and 302.

1. Method for adapting a number of radio bearers of a connection betweena user equipment and a Telecommunications network operating according toUniversal Mobile Telecommunication System standards from a first numberof radio bearers appropriate for a first service to a second number ofradio bearers appropriate for a second service, wherein the user usesthe first service when the second service is offered as a waiting call,the method comprising the steps of: indicating the beginning of theadaptation by sending a radio access bearer assignment message from amobile services switching centre to a radio network controller, sending,from the radio network controller to the user equipment, a radio bearersetup message for changing the number of radio bearers for theconnection, modifying the number of radio bearers supported for theconnection in the user equipment from the first number of bearers to thesecond number of bearers, acknowledging the modification by sending aradio bearer setup complete message from the user equipment to the radionetwork controller, and indicating the completion of the adaptation tothe mobile services switching centre by sending a radio access bearerassignment response message from the radio network controller to themobile services switching centre.
 2. Method according to claim 1, withthe additional steps of: sending, from the radio network controller tothe user equipment, a radio bearer release message for reducing thenumber of radio bearers for the connection, reducing the number of radiobearers that are supported for the connection in the user equipment, andacknowledging the reduction of the number of bearers by sending a radiobearer release complete message from the user equipment to the radionetwork controller.
 3. Method according to claim 2, wherein the userequipment keeps a mobility management context and the call controlcontext at the step of changing the number of radio access bearersincluding the change of radio bearers.
 4. Method according to claim 3,with the additional steps of: sending a release request message from theradio network controller to the mobile services switching centre torelease the connection for the first service, releasing the connectionfor the first service and sending a release confirm message from themobile services switching centre to the radio network controller,sending an establishment request message from the radio networkcontroller to the mobile services switching centre to set up aconnection for the second service, setting up a connection for thesecond connection and sending an establishment confirm message from themobile services switching centre to the radio network controller toconfirm the setup of the connection for the second service.
 5. Methodaccording to claim 4, wherein the setting up of the second connection isperformed before the releasing of the first connection.
 6. Methodperformed in a user equipment for adapting a number of radio bearers ofa connection between the user equipment and a Telecommunications networkoperating according to Universal Mobile Telecommunication Systemstandards from a first number of radio bearers appropriate for a firstservice to a second number of radio bearers appropriate for a secondservice, wherein the user uses the first service when the second serviceis offered as a waiting call, the method comprising the steps of:receiving, from a radio network controller of the telecommunicationsnetwork, a radio bearer setup message for changing the number of radioaccess bearers for the connection, changing the supported number ofradio bearers for the connection from the first number of bearers to thesecond number of bearers, acknowledging the modification by sending aradio bearer setup complete message to the radio network controller;receiving from the radio network controller a radio bearer releasemessage for reducing the number of radio bearers for the connection;reducing the number of radio bearers that are supported for theconnection; and acknowledging the reduction of the number of bearers bysending a radio bearer release complete message to the radio networkcontroller.
 7. Method according to claim 6, wherein the user equipmentkeeps a mobility management context and the call control context at thestep of changing the radio access bearer that includes the change ofnumber of radio bearers.
 8. Method performed in a radio networkcontroller of a Telecommunications network operating according toUniversal Mobile Telecommunication System standards for adapting anumber of radio bearers of a connection to user equipment from a firstnumber of radio bearers appropriate for a first service to a secondnumber of radio bearers appropriate for a second service, wherein theuser uses the first service when the second service is offered as awaiting call, the method comprising the steps of; receiving, from amobile services switching centre a radio access bearer assignmentmessage for indicating the start of the adaptation of radio accessbearers, sending to the user equipment a radio bearer setup message forchanging the number of radio bearers for the connection, receiving aradio bearer setup complete message from the user equipment as anacknowledgment for the change of the number of radio bearers supportedby the user equipment for the connection, and sending a radio bearerassignment response message to the mobile services switching centre toindicate the completion of the adaptation; sending to the user equipmenta radio bearer release message for reducing the number of radio bearersfor the connection, receiving a radio bearer release complete messagefrom the user equipment as an acknowledgment for the reduction of thenumber of bearers supported for the connection by the user equipment. 9.Method according to claim 8 with the additional steps of: sending arelease request message to the mobile services switching centre torelease a connection for the first service, receiving a release confirmmessage from the mobile services switching centre confirm message,sending an establishment request message to request the set up of aconnection for the second service, and receiving an establishmentconfirm message.
 10. Method according to claim 8, wherein theestablishment of a connection for the second service is performed beforereleasing the connection for the first service.
 11. Method according to10, wherein the sequence of establishment and release of a connectiondepends on a parameter value received from the mobile services switchingcentre.
 12. Method performed in a mobile services switching centre of aTelecommunications network operating according to Universal MobileTelecommunication System standards for adapting a number of radiobearers of a connection to user equipment from a first number of radiobearers appropriate for a first service to a second number of radiobearers appropriate for a second service, wherein the user uses thefirst service when the second service is offered as a waiting call, themethod comprising the steps of: sending, to a radio network controller aradio access bearer assignment message for indicating the start of theadaptation of the number of radio access bearers, and receiving a radiobearer assignment response message from the radio network controller asan indication of the completion of the adaptation; receiving a releaserequest message from the radio network controller for releasing aconnection for the first service, releasing the first connection for thefirst service, sending a release confirm message to the radio networkcontroller, receiving an establishment request message from the radionetwork controller for the set up of a connection for the secondservice, setting up the connection for the second service, and sendingan establishment confirm message to the radio network controller.
 13. Anapparatus for adapting a number of radio bearers of a connection betweenthe user equipment and a Telecommunications network operating accordingto Universal Mobile Telecommunication System standards from a firstnumber of radio bearers appropriate for a first service to a secondnumber of radio bearers appropriate for a second service, wherein theuser uses the first service when the second service is offered as awaiting call, the apparatus comprises: means for receiving, from a radionetwork controller of the telecommunications network, a radio bearersetup message for changing the number of radio access bearers for theconnection; means for changing the supported number of radio bearers forthe connection from the first number of bearers to the second number ofbearers; and means for acknowledging the modification by sending a radiobearer setup complete message to the radio network controller; means forreceiving from the radio network controller a radio bearer releasemessage for reducing the number of radio bearers for the connection,means for reducing the number of radio bearers that are supported forthe connection, and means for acknowledging the reduction of the numberof bearers by sending a radio bearer release complete message to theradio network controller.
 14. The apparatus of claim 13, furthercomprising means for maintaining a mobility management context and thecall control context when changing the radio access bearer, thatincludes the change of number of radio bearers.